Audi has been keeping up with TPMS technology since 2002. Starting with the optional system on the A8 and S8, they then threw the system on their whole line to comply with the recent law. They have used several valve sensors. The basics of the direct TPMS is that it uses a sensor in the wheel/tire to wirelessly relay pressure back to the driver on some sort of display. Some vehicles have a digital info screen that will show all four tire pressures (five pressures if spare has sensor) all the time. While others might just flash a low-tire-pressure light on the dash. There are also two different styles of sensors for this system: a valve sensor and a strap/band sensor. Only valve sensors are used by the direct system-equipped Audi, although if you bought an aftermarket SmarTire TPM system, those use the sensors held on by a strap around the barrel of the wheel.
The tire pressure indicator in the instrument cluster informs you if the tire pressure is too low or if there is a system malfunction. These characteristics can change and cause a tire pressure warning if the tire pressure in one or more tires is too low; the tire has structural damage; or the tire pressure was changed or the wheels rotated or replaced but the TPMS was not reset. An indirect tire pressure monitoring system (TPMS) compares the tire tread circumference and vibration characteristics of the individual tires. If the pressure decreases in one or more tires, this is indicated in the instrument cluster with a warning symbol.
Tire pressure monitoring systems (TPMS) are now impossible to run from when buying a new vehicle. Every new vehicle made for sale in the USA has a TPM system as standard equipment. There are a few exceptions though: the vehicle must have only four wheels (so no dual-wheeled trucks or motorcycles), and the GVWR must be less than 10,000lbs.
We do our best at TPMS DIRECT to guarantee proper fitment. We stock all parts for all makes/models Audis, we buy in large quantities direct from the manufacturer to guarantee availability and best prices around!